Context. Acoustic treatment and room correction based on digital signal processing are complex topics for most in the audiophile community. The same topics meanwhile are on very friendly terms with home-theater enthusiasts who often benefit from active correction that is integrated directly into their home-theater amplifiers or active subwoofers. Nevertheless the majority of audiophiles has almost caught on by now that the weakest element of any high-fidelity system is their room. Typical rooms introduce more than ±10dB frequency response variations whilst loudspeakers with truly perfect impulse response do not really exist in the first place.

But active correction remains not only a complex field of investigation. It’s also a source of paradox. The first paradox is the opposition between modified signal versus integrity of what in fact was recorded. Audiophiles usually demonstrate strong attractions to all conceivable kinds of sonic benefits (often by way of most curious devices) but remain scared by the potentially undesirable effects and collateral damages from any kind of digital compensation. Any loss of transparency or change in tonal balance would thus automatically discredit the guilty room correction system or its ability to be configured easily. Audiophiles have been raised in a particular cultural background. That has been focused on signal preservation. Active room correction champions the opposite though it deals with a strategic sum of alterations—the room + compensation—which in theory should cancel out to syncretize a perfectly preserved recorded signal.

The second paradox resides in the relative imperfection of active correction. Usually when one corrects anything, the very word ‘correction’ implies perfection or rightness. In the world of acoustics however one leaves behind the binary realm of right/wrong. It would perhaps be more adequate to speak of active reduction of room/speaker-induced distortion. There is in fact a physical limit to how much correction can be applied without imposing undesirable effects. Room acoustics themselves impose practical limitations too. We thus can hardly define acoustic perfection other than as an abstract. We simply do not live in or experience anechoic reality. Our listening experiences and personal references are completely different.

Acoustic treatment encounters further limitations of several orders - aesthetics, cost and geometry for instance. Passive correction benefits depend on the nature of our listening room. If too problematic, we might spend an inordinate amount of money to fix things that should have been rejected in the first place. The most radical solution would be designing and building a dedicated listening room from scratch as a kind of personal concert hall. But who can afford that even if they own rather than rent? And who then has access to experts with a proven track record in that domain? The stories of listening rooms designed according to geometric formulae which didn't perform as promised are legion.